s, the height; and the time meridian, the direction.

Thus (see map in pocket at back of book), Pope Hill (sm') is 800 yards
from Grant Hill (um') (using graphical scale), and it is 30 feet
higher than Grant Hill, since it is on contour 870 and Grant Hill is
on contour 840; Pope Hill is also due north of Grant Hill, that is,
the north and south line through Grant Hill passes through Pope Hill.
Therefore, the position of Pope Hill is fully determined with respect
to Grant Hill.

Orientation

=1872.= In order that directions on the map and on the ground shall
correspond, it is necessary for the map to be oriented, that is, the
true meridian of the map must lie in the same direction as the true
meridian through the observer's position on the ground, which is only
another way of saying that the lines that run north and south on the
map must run in the same direction as the lines north and south on the
ground. Every road, stream or other feature on the map will then run
in the same direction as the road, stream or other feature itself on
the ground, and all the objects shown on the map can be quickly
identified and picked out on the ground.

Methods of Orienting a Map

1st. By magnetic needle: If the map has a magnetic meridian marked on
it as is on the Leavenworth map (in pocket at back of book), place the
sighting line, a-b, of the compass (Fig. 15) on the magnetic meridian
of the map and move the map around horizontally until the north end of
the needle points toward the north of its circle, whereupon the map is
oriented. If there is a true meridian on the map, but not a magnetic
meridian, one may be constructed as follows, if the magnetic
declination is known:

(Figure 16): Place the true meridian of the map directly under the
magnetic needle of the compass and then move the compass box until
the needle reads an angle equal to the magnetic declination. A line in
extension of the sighting line a'-b' will be the magnetic-meridian. If
the magnetic declination of the observer's position is not more than
4 deg. or 5 deg., the orientation will be given closely enough for ordinary
purposes by taking the true and magnetic meridians to be identical.

2d. If neither the magnetic nor the true meridian is on the map, but
the observer's position on the ground is known: Move the map
horizontally until the direction of some definite point on the ground
is the same as its direction on the map; the map is then oriented. For